fix(button): preserve precise dimensions across garment handoffs

sew-through-button/README.md

@@ -0,0 +1,32 @@
+# Sew-through button dimensions
+
+Last Updated: 2026-09-30
+
+This cartridge owns the button solid; Fashion Cabinet owns garment sizing and
+the mapping from a garment to its hardware. See the
+[commons topology](../README.md#the-four-repo-topology) and
+[contribution rules](../CONTRIBUTING.md).
+
+The manifest accepts thickness, hole diameter and dish depth in 0.01 mm steps,
+and hole spacing in 0.005 mm steps. These steps preserve fine dimensions from
+garment mappings, including the ligne-to-millimetre conversion, without silently
+rounding them to the former coarse increments. They describe input resolution,
+not manufacturing accuracy. Existing bounds, integer ligne sizes, two/four-hole
+choices, geometry constraints and batch limits still apply.
+
+Three presets exercise the additional resolution:
+
+| Preset | Dimensions covered |
+| --- | --- |
+| `infant_precise` | 1.62 mm thickness, 1.08 mm holes, 3.24 mm spacing and 0.36 mm dish |
+| `placket_precise` | 24 L button with 5.08 mm hole spacing |
+| `small_precise` | 15 L button with 3.175 mm hole spacing |
+
+The source geometry is unchanged. Validation renders both modes and every
+preset with the [shared geometry gate](../README.md#validating-a-cartridge).
+Platforms must consume the updated manifest contract before the added input
+resolution is available in their handoffs. Values outside the declared grid,
+bounds or active mode remain unsupported.
+
+Private rollout evidence belongs in Internal DevOps under the
+[repository boundary](../docs/PUBLIC_REPO_BOUNDARY.md).

sew-through-button/project.json

@@ -143,7 +143,7 @@
       "default": 3.0,
       "min": 1.0,
       "max": 6.0,
-      "step": 0.2,
+      "step": 0.01,
       "group": "size",
       "modes": [
         "button",
@@ -185,7 +185,7 @@
       "default": 1.5,
       "min": 1.0,
       "max": 3.0,
-      "step": 0.1,
+      "step": 0.01,
       "group": "holes",
       "modes": [
         "button",
@@ -206,7 +206,7 @@
       "default": 4.0,
       "min": 2.0,
       "max": 12.0,
-      "step": 0.5,
+      "step": 0.005,
       "group": "holes",
       "modes": [
         "button",
@@ -227,7 +227,7 @@
       "default": 0.8,
       "min": 0.0,
       "max": 2.0,
-      "step": 0.1,
+      "step": 0.01,
       "group": "size",
       "modes": [
         "button",
@@ -312,6 +312,50 @@
         "dish_depth": 0.6,
         "card_count": 8
       }
+    },
+    {
+      "id": "infant_precise",
+      "mode": "button",
+      "label": {
+        "en": "Infant button (18 L, fine dimensions)",
+        "es": "Botón infantil (18 L, dimensiones finas)"
+      },
+      "values": {
+        "button_ligne": 18,
+        "thickness": 1.62,
+        "hole_count": 2,
+        "hole_dia": 1.08,
+        "hole_spacing": 3.24,
+        "dish_depth": 0.36
+      }
+    },
+    {
+      "id": "placket_precise",
+      "mode": "button",
+      "label": {
+        "en": "Shirt placket button (24 L, 5.08 mm spacing)",
+        "es": "Botón de cartera (24 L, separación de 5.08 mm)"
+      },
+      "values": {
+        "button_ligne": 24,
+        "hole_count": 4,
+        "hole_spacing": 5.08,
+        "hole_dia": 1.8
+      }
+    },
+    {
+      "id": "small_precise",
+      "mode": "button",
+      "label": {
+        "en": "Small button (15 L, 3.175 mm spacing)",
+        "es": "Botón pequeño (15 L, separación de 3.175 mm)"
+      },
+      "values": {
+        "button_ligne": 15,
+        "hole_count": 4,
+        "hole_spacing": 3.175,
+        "hole_dia": 1.6
+      }
     }
   ],
   "constraints": [